Process and apparatus for removing wax from oil



Feb. 1, 1927.

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SELIJEN H. HALL, OF POUGHKEEPSIE,

NEW YORK, ASSIGNOR TO THE DE LAVAL SEPARATOR COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

PROCESS AND APPARATUS FOR REMOVING WAX FROM OIL.

Application filed February 20, 1923. Serial No. 620,189.

My invention relates to the known process of separating wax from waxy mineral oil, said process comprising broadly diluting the oil with a light hydrocarbon, then chilling the solution to precipitate the wax and then centrifuging.

. The object of my invention is to conserve the diluent and provide a substantially continuous process for What is now a partially intermittent process.

In the known process, in order that the solvent action of the diluent (generally naphtha, benzine or gasoline, hereinafter called benzine) shall be complete and that there shall be no preliminary separation in the mixture storage tank, it is necessary that the oil and benzine be at a temperature high enough to cause complete'solution of the wax in the oil. It is often necessary that this temperature be as high as 90 F. or 100 F.

' When a tank full of oil and benzine is mixed and held at this high temperature for the time (sometimes several days) required to treat a full tank, there is a. large loss of benzine by evaporation.

The way in which I prevent this loss will be clear from the description that follows, it being understood that the apparatus shown and described, while new and useful, is not necessary to the execution of the process.

The accompanying drawing shows said apparatus diagrammatically.

a is a raw oil tank, I) a benzine tank, 0 an oil pump, and a3 a benzine pump. e is a heat exchanger and f a steam-heated heater. 7' and h are constant level tanks, the first for oil and the second for benzine. Floatoperated valves 2' and j control the flow of oil and benzine respectively to the tanks 9 and 72. respectively. 70 and l are metering nozzles extending from tanks 9 and it respectively and fed through stop cocks m and 0 is a small receiving tank into which the metering nozzles extend. is a mixer and g a seasoning tank. The seasoning tank connects, through heat exchanger .e and a water-cooled oil cooler z, with a feed tank 1' for the chiller s. In the tank 7- is a float t that controls the valves m and a. 'v is a float-controlled valve in the connection between tank 7* and chiller s. u

. is a centrifuge communicating with the chiller 8. w 'w w is a gas pressure equalizing pipe open to tanks 9, h, 0 and 1" and provided with a condensing coil 00. 3 is a coil extending into the chiller and in which circulates refrigerated brine.

In carrying out my process, oil and benzine from the tanks a and b, are forced b the pumps 0' and 03 through the heat exchangers e, Where they are partly heated. They then pass through the heater 7', receiving heat to bring them to the desired temperature, and through the float-controlled valves 6 and 7' enter the constantlevel tanks 9 and h. From the constant level tanks the oil and benzine flow to the metering nozzles 7c and Z, which are adjusted to feed them, in the proportionsto make the blend desired, into the tank 0 and thence into the mixer 1). After being thoroughly mixed, the blended oil is held 1n the seasoning tank q for a time to insure perfect solution of all wax. It then flows through the heat exchanger e, where it gives up much of its heat to the incoming oil and benzine, and then through the water-cooled cooler a to the small storage tank 7, from which it flows to the chiller s as required. The float-controlled valve '0 admits the solution or blend to the top of the chiller continuously as fast as it is removed from the bottom by the centrifuge u.

In order that the metering nozzles 74 and Z may properly proportion the oil and benzine, it is necessary that they have at all times either a full flow or no 'fl0W-' The float t in the tank 7' is so connected to the valves m and n that the valves will suddenly open wide when the tank is nearly'empty and close tight when it is nearly full.

The entire apparatus is completely enclosed so that oil, benzine and solution have no contact with the atmosphere from the time they leave the supply tanks a and 5 until the cold mixture is about to enter the centrifuge u. The only vent from the ap parat-us is by the gas pressure equalizing pipe w through the condenser coil. When p in operation, the air in the tops of the tanks 9', h, 0 and 1' will soon become so saturated with vapor as to stop further evaporation. The small amountot air that passes in and out due to changes of level in the tank 251 will be so cold in the coil m that most of the vapor in it will be condensedand recovered.

From the above it will be understood that I have provided a process which will reduce to a minimum evaporation losses and heat required and reduce the temperature of the oil entering the chiller to approximately that of the coolest water available.

The precise arrangement of parts shown, or the arrangement of the parts shown in the order shown, is not necessary to the successful use of the apparatus. For ex ample, it is not necessary to use tanks to secure constant pressure on the metering nozzles la and Z. Nor is it necessary to apply heat separately to the oil and diluent, as distinguished from applying it to the mixture, in order to secure complete solution of the wax. Where, therefore, in the claims I specify a series of successive operations or a series of elements through which the oil and diluent flow successively, I do not mean to be limited to the precise order in which said operations'or elements are enumerated, except where, in certain specific claims, any other order or arrangement is necessarily excluded by the language used.

Having now fully described my invention, what I claim and desire to protect by Letters Patent is:

1. The process of removing wax from waxy mineral oil which comprises flowing separate streams of waxy oil and a diluent from sources of supply into two separate bodies of said oil and diluent and beating them en route, feeding both materials at a regulated rate from said separated bodies and mixing and blending them, flowing the heated solution in heat exchange relation with said separate streams flowing toward said separate bodies before heating the materials of said streams as aforesaid, whereby the materials inthe separate streams are pre-heated and the flowing solution is precooled, chilling the solution, and separating the wax from the oil.

2. The process of removing wax from waxy mineral oil which comprises flowing waxy oil and a diluent from separate bodies of the same, mixing and blending them, accumulating the diluted waxy oil, rendering said flow intermittent by the rise and flow of the level of the accumulating diluted waxy oil, flowing the diluted waxy oil from. the locus of accumulation, chilling the flowing diluted waxy oil to precipitate the wax and separating the oil and wax.

3. The process of removing wax from mineral oil which comprises feeding waxy oil and adiluent from separate bodies of the same, mixing and blending them, accumulating the solution, flowing the solution from the source of accumulation at a rate.

below the rate of accumulation, chilling the outflowing solution, separating the oil and wax, shutting off the feed when the solution accumulates to a predetermined degree,

maintaining the feed shut off until the volumes of the accumulated solution diminishes to a predetermined degree, and then restormg the feed to allow i e-accumulation ot the solution.

4. The process of removing wax from waxy mineral oil which comprises feeding such waxy oil and a diluent from separate bodies of the same and mixing them in the course of their flow, flowing-the mixture from the locus of mixing and holding the mixture in a body to insure solution of the wax, flowing a stream of the solution from said body and preliminarily cooling it, accumulating the cooled solution, flowing the solution from the locus of accumulation, at a rate below that at which the waxy oil and diluent flow to the mixture, and utilizing the accumulating liquid to regulate the flow of waxy oil and diluent toward the locus of mixing. p

5. The process of recovering wax from waxy mineral oil which comprises feeding such waxy oil and a diluent from separate bodies of the same and mixing and blending them, establishing a flow of said blended material and in the course of its flow chilling the same to precipitate the wax and subjecting the chilled mixture to centrifugal force to effect the separation of the wax from the oil, regulating the flow of the solution toward the locus of precipitation in accordance with the rate of flow of the chilled mixture to the locus of separation, and regulating the feed of the waxy oil and diluent in accordance with the flow of the solution toward the locus of precipitation of wax.

6. The process of removing wax from waxy mineral oil which comprises feeding waxy mineral oil and a heated diluent respectively to separate bodies of said oil and diluent, separately discharging said oil and diluent and establishing a flow of said oil and diluent to a locus of separation and in the course of such flow subjecting them to successive mixing, blending. cooling and chilling and between the cooling and chilling of the mixture maintaining a body of the cooled mixture, and in accordance with the rise and fall of the level of the cooled mixture in said body intermittently stopping and starting the flow from the separate bodies of oil and diluent simultaneously.

7. Apparatus for recovering wax from waxy mineral oil comprising two separate tanks, conduits connected witli the respective tanks and through which the oil and a diluent are adapted to How to the respective tanks, means adapted to feed from the receptacles substantially constant proportions of the materials therein, a mixer and blender adapted to operate on the materials fed from said receptacles, a conduit leading from the mixer and blender in heat exchange relation with the first two conduits, a fourth conduit communicating with the third con- 1 duit, a chiller adapted to precipitate the waxy mineral oil,

wax in the course of the flow of the blended stock through the fourth conduit, and means to continuously separate the precipitated Wax from the oil 8. Apparatus for recovering wax from comprising two separate tanks, conduits connected Wlth the respective tanks, said tanks tive tanks and through which the oil and a diluent are adapted to flow to the respechaving outlets, valves controlling said outlets, a mixer and blender 1n communicationwith said valved outlets,

a vessel in communication with said mixer and blender, a chiller through which the blended stock is adapted to flow from said vessel, a separator communicatin with said chiller, andvmeans operable by he rise and fall of the blended stock in said vessel to alternately open both said valves when the level of stock therein is relatively low 'and close both saidvalves when the level is relati vely high.

In testimony of which invention I have hereunto set my hand, at Poughkeepsie, 1N Y., on this 12th day of Febrguary, 1923.

SELDEN; H. HALL. 

